CN1171408C - Method and device for generating real-time channel code sequence in WCDMA system - Google Patents

Abstract

The present invention discloses a real-time production method and a device for OVSF codes of orthogonal and variable spreading factors in communicating field. In the real-time production method, according to encoding characteristics of the OVSF codes, a generating method of OVSF codes with different code length is converted into a generating method of OVSF codes with fixed code length; meanwhile, OVSF code numbers and the counting of each OVSF code have specific relation; OVSF code sequence can be generated in high speed and real time according to the relation. The device comprises methods of code length conversion and high-speed OVSF code generation. The method and the device of the present invention can generate the OVSF codes in high speed, which is directly completed by a simple universal circuit device. Thus, implementation procedures are simplified, and system soft hardware is saved.

Description

The method and apparatus of generating real-time channel code sequence in a kind of WCDMA system

Technical field

The present invention relates to Wideband Code Division Multiple Access (WCDMA) WCDMA (the Wide Code Division MultipleAccess) system of communication field, be specifically related to the method and apparatus of generating real-time channel code sequence in the multi-address communication system of broadband.

Background technology

WCDMA is a kind of broadband CDMA system, and the information bit of different channels is distinguished with different sign indicating number sequences.Relate to two kinds of sign indicating number sequences in the WCDMA system, a kind of is scrambler sequence, and another kind is a channel code sequence.Scrambler has reasonable auto-correlation and cross correlation, and channel code adopts variable bandspread factor OVSF (Orthogonal Variable Spreading Factor) sign indicating number, and it has good orthogonality, cross-correlation function value synchronously the time be 0.Therefore channel code has important effect in system, and it can distinguish different channels under same scrambler, simultaneously because the characteristics of variable bandspread factor make system can change channel data transmission speed easily.The length of sign indicating number and the orthogonal code number of same length equate, when using the channel code modulation intelligence bit of certain-length, are exactly the spread spectrum process to information bit, and therefore the length of sign indicating number is called spreading factor (SpreadFactor SF) again.Being defined in the information rate of transmitting on the physical layer in the WCDMA system fixes, be 3.84Mbps, but because diversity of operations and the professional randomness that produces, the transmission rate that requires each channel energy data carried by data again should be that unit changes with the frame, and for the transport layer data of the physical layer channel carrying different rates that reaches constant transmissions speed, the approach that is adopted just is to use the spreading code of different spreading factors.Channel is a dynamic process as its assignment of a kind of resource and use, and the processing speed of information in transmission course directly influences the performance of system, so produce the channel appointed sign indicating number rapidly with simple algorithm, and to take less hardware resource be very important to the WCDMA system.

The direct production method of channel code sequence is fairly simple, and the sign indicating number sequence that length is spreading factor can be released by the sign indicating number sequence of length=SF/2, and length=SF/2's again can be by the sign indicating number sequence release of length=SF/4, and length=1 yard always 1.Just can obtain the required sign indicating number sequence that gets through the anti-phase recursion of one-level level like this.But high because spreading rate requires, said method requires when hardware is realized, needs to preserve all bits in hardware unit inside and calls repeated use for channel.Because system will support a large amount of channels, it is very huge that the hardware resource that causes like this takies.If can use spreading factor SF according to the characteristic of channel code sequence, sign indicating number K (4≤K≤SF-1) directly draw channel code sequence bit C by simple algorithm with a sign indicating number bit count value i (0 to SF-1) _{SF, K}(i) value (1 or-1), this will save a large amount of hardware resources.

Summary of the invention

One of purpose of the present invention is to provide the method that channel code sequence produces in a kind of WCDMA system.

Two of purpose of the present invention is to provide the channel code generation device that adopts said method in a kind of WCDMA system.

The generation method of WCDMA system channel sign indicating number sequence of the present invention may further comprise the steps:

Step 1: given desire produces the parameter value of channel code sequence;

Step 2: the channel code sequence parameter value is expressed as binary system;

Step 3: the channel code sequence of different code length degree is converted into same code length channel code sequence;

Step 4: bit counting I=O;

Step 5: if I=SF _Max, then get back to step 4, otherwise continue;

Step 6: with the highest order of k with the time high-order of the lowest order of I and, k and I low level with, up to the highest order of the lowest order of k and I with;

Step 7: the parity of 1 number among the calculating gained result;

Step 8; If 1 number is strange, bit gets-1, otherwise gets 1;

Step 9: make I=I+1; Jump to step 5;

In the generation method step 1 of above-mentioned channel code sequence, provide spreading factor SF, the sign indicating number K that will produce channel code sequence, also will provide the desired maximum spreading factor SF of this channel simultaneously _Max

In the generation method step 3 of above-mentioned channel code sequence, the channel code sequence of different code length degree is converted into the equal length channel code sequence is meant that according to the maximum possible spreading factor with sign indicating number k, spreading factor shifts left, the rightest bit is filled with 0, if SF＜SF _Max, continue displacement up to SF=SF _Max

The figure place that K moves to left is identical with the figure place that SF moves to left, the channel code sequence CSF that will produce after moving to left _{Max, K '}Be exactly C _{SF, K}The circulation of sign indicating number sequence repeats the C of generation _{SFmax, K '}The sign indicating number sequence can be by C _{SF, K}Recycling.

Carry out a yard sequence bits position counting i.Because the sign indicating number sequence produces by turn, every generation one bit code is just counted number one time, and promptly i adds 1; The inverted order of K ' binary value and the binary value i of current bit count value are carried out step-by-step and calculating, that is to say with the highest order of K ' with the lowest order of current bit count value i with, the inferior low level of time high-order and bit count value i of K ' with, and the like, up to the highest order of the lowest order of K ' and bit counting i and and preservation, step 6 with after the result deliver in the middle of next step;

In the generation method step 7 of above-mentioned channel code sequence, 1 number among the result of calculation procedure 6 gained decides current code value according to the parity of its number, i.e. current sign indicating number sequence bits C during even number 1 _{SFmax, K '}(i) value is 1, otherwise gets-1.This O-SFmax-1 sign indicating number sequence is exactly C _{SF, K}(i) press the repetition of 0-SF-1 sign indicating number sequence, can be used for C _{SF, K}(i) repeated use.

A kind of channel sequence sign indicating number generation device based on said method comprises: the sign indicating number shift unit, and the bit counter, the odd even determining device:

Described sign indicating number shift unit is finished the displacement of spreading code number, and input code number is shifted according to the proportionate relationship of spreading factor and maximum spreading factor;

Described bit counter is counted the sign indicating number that will produce, again the inverted order step-by-step of the spreading code after the displacement that produces with sign indicating number shift unit number with, and the general with the result offer the odd even determining device;

Described odd even determining device judge above-mentioned bit counter module with the result in the parity of 1 number, get value thereby draw current bit.

The invention provides quick, simple, general implementation method that produces the Orthogonal Variable Spreading Factor OVSF channel code sequence and the device of realizing the method for the invention.Described method provides effective production method for the generation of the channel code sequence of multichannel different length in the broadband CDMA system, and the channel code sequence of different length is produced the channel code sequences column-generation that is converted to regular length, has formed a kind of universal architecture; Simultaneously, the generation of each bit of the sign indicating number sequence relation by sign indicating number sequence number and bit count is generated in real time, effectively raise real-time and save memory space, simplify implementation procedure, save system hardware and software.

Description of drawings

The present invention is described in further detail below in conjunction with drawings and Examples.

Fig. 1 is the generation formula figure of channel code;

Fig. 2 is the tree structure figure of channel code;

Fig. 3 is the method flow that the OVSF channel code produces;

Fig. 4 is a WCDMA base band spread processing exemplary functions block diagram;

Fig. 5 is a plurality of channel code functional block diagrams of generator simultaneously;

Fig. 6 is the detailed installation drawing of individual channel sign indicating number generator;

Embodiment

Fig. 1 is the generation formula figure of channel code.It is a kind of sign indicating number sequence of deriving by recursion method, its length can be 2 n power (n=0,1 ...).The length of sign indicating number and the orthogonal code number of same length equate, when using the channel code modulation signal bit of certain-length, are exactly the spread spectrum process to signal bit, and therefore the length of sign indicating number is called spreading factor (Spread Factor SF) again.Traditional method can have the relational expression of Fig. 1 directly to release all bits of a channel code, but it need be preserved when all bits use for channel and call, because the spread spectrum and the despreading of large volumes of channels will be supported in the base station, if adopt this method, just need a large amount of resources, this method is obviously inadvisable.

Fig. 2 is the tree structure figure of channel code; When SF equaled 1, value was (1) in the figure; During SF=2, can equal 1 sign indicating number by SF and release, two kinds of sign indicating number sequences are arranged, assigned code number is 0 and 1 in order.Sign indicating number number be 0 be SF to be equaled 1 sign indicating number sequence repeat one times, add in the back formation (1,1); Sign indicating number number be 1 be SF to be equaled 1 sign indicating number sequence inversion, add in the back formation (1 ,-1).Same SF equals at 4 o'clock, sign indicating number number be 0 and 1 can to equal 2 sign indicating number by SF number be that 0 sign indicating number sequence is released, sign indicating number number be 2 and 3 can to equal 2 sign indicating number by SF number be 1 sign indicating number sequence release.In like manner and the like, can draw the higher sign indicating number preface of SF.Channel code can show with tree structure visually, each yard sequence all can generate the sign indicating number of length for its twice, also we can say the sign indicating number sequence that all comprises in each higher leveled code tree in all rudimentary code tree, and be the repetition of the sign indicating number sequence in the rudimentary code tree.Among the present invention the channel code of variable-length is generated the method for the channel code generation that is converted into regular length, just be based on this specific character of channel code.

Fig. 3 is the flow chart of channel code production method of the present invention;

At first we analyze the sign indicating number sequence of channel code, establish the n power of SF=2, and then sign indicating number number available n bit binary number is represented (c _N-1c _N-2C ₁c ₀), c wherein _N-1Be highest order, c ₀Be lowest order; The bit of sign indicating number sequence also can be expressed as (b _N-1b _N-2B ₁b ₀), b wherein _N-1Be last bit, b ₀Be first bit.Have a look each value of yard sequence again, all can regard 1 as through obtaining after the negate for several times.If each yard sequence is divided into two by code length, so latter half of is duplicating or negate of first half, promptly latter half of bit than the first half bit Duo a negate may, negate is then decided by the parity of sign indicating number number, that is to say the c by sign indicating number number ₀Bit decides, c ₀Be that 1 time-code number is odd number, then the latter half bit is the negate of first half bit, c ₀Be that 0 time-code number is even number, then the latter half bit is duplicating of first half bit.If sequence one is divided into four parts, odd number part is the possibility of the many negates of antithesis fractional part again, and the parity that number divided exactly after 2 by sign indicating number of negate decides, just by the c of sign indicating number number ₁The bit decision, c ₁Be that 1 time-code number is odd number negate, c ₁Be that 0 time-code number duplicates for even number.By that analogy, when sequence is divided into the SF/2 part, the many negate chances of the same antithesis fractional part of odd number part, negate is by the c of sign indicating number number _N-1The bit decision.

Above-mentioned analysis as can be known, for a sequence of known code number, the value of certain bit can be determined by the position in the sequence at its place like this.Work as b _N-1=1 o'clock, clearly this bit was at the latter half of sequence.Work as b _N-2=1 o'clock, this bit was in the odd number part of the sequence quartering, is extrapolated to b ₀=1 this bit is in the odd number part of SF/2 equal portions.So b _N-1﹠amp; c ₀b _N-2﹠amp; c ₁B ₀﹠amp; c _N-11 number is exactly the number of times of this bit negate among the gained result.

Secondly, if can produce channel code under the different SF, then ideal with identical method.From what has been discussed above, we can notice: (SF, K) (2*SF 2*K) has identical sign indicating number sequence to channel code, and just message transmission rate is with the speed ratio difference of sign indicating number sequence with channel code.Therefore the generation of different SF lower channel sign indicating numbers all can be summed up in the point that SF _MaxUnder production, grasp this rule, just can produce the sign indicating number sequence under the different SF with identical method at an easy rate.

According to above analysis, just obtain producing the algorithm of channel code sequence:

1 given desire produces the spreading factor SF of channel code sequence, sign indicating number k, maximum possible spreading factor SF _Max

2 with spreading factor SF, sign indicating number k, maximum possible spreading factor SF _MaxAll be expressed as binary system;

3 shift left sign indicating number k and SF simultaneously, and the rightest bit is filled with 0, if SF＜SF _Max, continue displacement up to SF=SF _Max

4 bits counting I=O;

If 5 I=SF _MaxThen get back to step 4; Otherwise continue

6 with the highest order of k with the time high-order of the lowest order of I and, k and I low level with, up to the highest order of the lowest order of k and I with;

The parity of 1 number among the 7 calculating gained results;

If 81 number is strange, bit gets-1, otherwise gets 1;

9 I=I+1; Jump procedure 5;

Like this with regard to generation capable of circulation channel code sequence bit arbitrarily.

Fig. 4 is that a plurality of ovsf code synchronizers are used block diagram the typical case of WCDMA base band spread processing, and it comprises several sections: at first carry out code interleaving by 001 pair of source data of code interleaver and be formed for the data that physical channel transmits; Then through produce the spread spectrum of channel code sequence by a plurality of channel code sequence synchronizers 002; Pass through weighted again; Carry out scrambler through scrambling generator 003 at last, offer system's next stage modulator.

Above-mentioned code interleaver 001 carries out code interleaving and rate-matched with the former data of various speed in the WCDMA Base-Band Processing, and forms the data of respective physical Channel Transmission, and for different physical channels, data rate at this moment is different.

The sign indicating number of the spreading channel code that above-mentioned a plurality of ovsf code synchronizer 002 provides according to each channel of system number and SF value, produce the required channel code sequence of each channel, dateout to code interleaver 001 is carried out spread spectrum, forms the fixed rate 3.84Mbps data of physical channel transmission.

Data behind the spread spectrum are weighted processing with a pre-determined factor.

Above-mentioned scrambler generator 003 can produce the two-way scrambler simultaneously, and respectively to I, the Q two paths of signals carries out scrambling.Scrambled signals is delivered to modulators modulate at last.

Handle for the despreading of WCDMA base band, similar to spread spectrum, just flow process is opposite.They all can use channel code generator 002 simultaneously, just no longer describe in detail.

Fig. 5 is a plurality of channel code channel code sequences functional block diagrams of generators simultaneously, and it is by sign indicating number shift unit 101, the public counter 102 in N position, and odd even determining device 103 is formed.

At first, the spreading factor of sign indicating number that is provided with according to system number and maximum possible, with above-mentioned shift unit 101 shifting processing of sign indicating number process that system is provided with, be created under the maximum spreading factor yard number, binary height bit reversal that then will this sign indicating number number is delivered in the odd even determining device 103.

Simultaneously, public counter 102 begins to carry out the bit counting, whenever will produce a sign indicating number bit, and counter adds 1, and count value is also delivered in the odd even determining device 103.

Then odd even determining device 103 data that shift unit 101 and public counter 102 are provided carry out step-by-step with calculating, judge again with after the result in 1 number, sign indicating number shift unit 101 modules.

In the W-CDMA system, transmitting terminal can produce a plurality of different spreading factors simultaneously synchronously, and the channel code of different code numbers just can produce different sign indicating number sequences simultaneously according to the method for front in a device.As shown in Figure 5, public counter 101, its circulation produces from 0 to SF _Max-1 bit counting, sign indicating number shift unit 101 is separately according to different sign indicating numbers number and the SF variation that is shifted, displacement back sign indicating number number is delivered to the odd even determining device and is carried out with bit counter output valve and operate after high low level reversed order, the parity of 1 number in the judged result again, according to the parity difference, obtain current bit, thereby obtain sign indicating number sequence separately.

Fig. 6 is the detailed installation drawing of individual channel sign indicating number generator, comprises public counter 102 modules in N position, odd even determining device 103 modules.

Above-mentioned sign indicating number shift unit 101 modules are finished the sign indicating number shift function.Can find out that from the recurrence formula of front (SF, K) (2*SF 2*K) has identical sign indicating number sequence to channel code, and just message transmission rate is with the speed ratio difference of sign indicating number sequence with channel code.Therefore produce arbitrarily (SF, sign indicating number K) all can regard as generation (512, I*K) (descending) or (256, the I*K) sign indicating number of (up), I=512/SF (descending) or 256/SF (up).The value of K ' when this sign indicating number conversion process shifts left K to SF=512 (descending) or 256 (up) is exactly filled with 0 during displacement.The sign indicating number shift unit is just realized this function, and the physical circuit of sign indicating number shift unit realizes it being that to have adopted SF be the multidiameter option switch of control signal.Produce different SF like this and only need a kind of structure.

Above-mentioned N digit counter 101 modules are finished the tally function of each yard of sequence position.Its circulation produces from 0 to SF _MaxThe counting of-1 sequence bits position.In down channel, maximum available SF _Max=512; In up channel, maximum available SF _Max=256; Minimum available SF=4.So the figure place of counter, up N=9, up N=8.

Above-mentioned odd even judges that 103 modules finish the function that odd even is judged.With the highest order of the sign indicating number of sign indicating number shift unit 101 modules output number with the count value of counter 101 modules output get lowest order and, sign indicating number number output time high-order with count value time low level and, the lowest order of number exporting up to sign indicating number and counter highest order with.Then by XOR handle to judge all with the result in the parity of 1 number, thereby obtain a yard sequence value, sign indicating number shift unit 101 modules.

Claims (7)

1, the method for generating real-time channel code sequence in a kind of WCDMA system is characterized in that may further comprise the steps:

Step 1: given desire produces the parameter value of channel code sequence;

Step 2: the channel code sequence parameter value is expressed as binary system;

Step 3: the channel code sequence of different code length degree is converted into same code length channel code sequence;

Step 4: bit counting I=0;

Step 5: if I=SF _Max, then get back to step 4, otherwise continue;

Step 6: with the highest order of k with the time high-order of the lowest order of I and, k and I low level with, up to the highest order of the lowest order of k and I with;

Step 7: the parity of 1 number among the calculating gained result;

Step 8; If 1 number is strange, bit gets-1, otherwise gets 1;

Step 9: make I=I+1; Jump to step 5;

In the above step, SF _MaxBe maximum spreading factor, K is a bandspread factor code number, and I is the bit counting.

2, the method for generating real-time channel code sequence in the WCDMA according to claim 1 system, it is characterized in that: described step 1 is meant and provides spreading factor SF, the sign indicating number K that will produce channel code sequence, also will provide the desired maximum spreading factor SF of this channel simultaneously _Max

3, the method for generating real-time channel code sequence in the WCDMA according to claim 1 system, it is characterized in that: described step 3 is converted into same code length channel code sequence with the channel code sequence of different code length degree and is meant according to the maximum possible spreading factor sign indicating number k, spreading factor shifts left, the rightest bit is filled with 0, if SF＜SF _Max, continue displacement up to SF=SF _Max

4, the method for generating real-time channel code sequence in the WCDMA according to claim 3 system, it is characterized in that: described spreading factor is with sign indicating number k, spreading factor shifts left and is meant that the figure place that K moves to left is identical with the figure place that SF moves to left, the channel code sequence C that will produce after moving to left _{SFmax, K}' be exactly C _{SF, K}The circulation of sign indicating number sequence repeats the C of generation _{SFmax, K '}The sign indicating number sequence can be by C _{SF, K}Recycling.

5, the method for generating real-time channel code sequence in the WCDMA according to claim 1 system is characterized in that: if described I=SF _MaxThen get back to bit counting I=0, otherwise continue to be meant that carrying out yard sequence bits position counts an I, the inverted order of K ' binary value and the binary value i of current bit count value are carried out step-by-step and calculating, with the highest order of K ' with the lowest order of current bit count value i with, the inferior low level of time high-order and bit count value i of K ' with, and the like, up to the highest order of the lowest order of K ' and bit counting i and and preservation, step 6 with after the result deliver in the middle of next step.

6, the method for generating real-time channel code sequence in the WCDMA according to claim 1 system is characterized in that:

1 number among the result of calculation procedure 6 gained decides current code value according to the parity of its number, i.e. current sign indicating number sequence bits CSF during even number 1 _{Max, K '}(i) value is 1, otherwise gets-1, and this 0-SFmax-1 sign indicating number sequence is exactly C _{SF, K}(i) press the repetition of 0-SF-1 sign indicating number sequence, can be used for C _{SF, K}(i) repeated use.

7, the device of generating real-time channel code sequence in a kind of WCDMA system is characterized in that comprising the sign indicating number shift unit, the bit counter, and the odd even determining device:

Described sign indicating number shift unit is finished the displacement of spreading code number, and input code number is shifted according to the proportionate relationship of spreading factor and maximum spreading factor;

Described bit counter is counted the sign indicating number that will produce, again the inverted order step-by-step of the spreading code after the displacement that produces with sign indicating number shift unit number with, and the general with the result offer the odd even determining device;

Described odd even determining device judge above-mentioned bit counter module with the result in the parity of 1 number, get value thereby draw current bit.

Images